Lanthanum

Lanthanum is the first of the lanthanides, the rare-earth metals that sit in their own row below the main periodic table. Carl Gustaf Mosander discovered it in 1839, hidden in a cerium mineral, and named it from the Greek for to lie hidden. It is mined with other rare earths from minerals such as bastnäsite and monazite, mostly in China.

Lanthanum oxide makes glass bend light strongly with little color fringing, so it is used in high-quality camera lenses. The nickel-metal hydride batteries in many hybrid cars contain lanthanum, and it helps catalysts crack crude oil into gasoline.